Earlier this month, after speaking with our realtor, we contacted Chimney Sweeps of America and requested that they come out to clean and inspect our fireplace before we put our house on the market.
The came out and looked at our zero clearance fireplace (we found out later) and saw that it did not need cleaned, but there was a crack in the back refractory panel and it needed replaced since it was not safe to use.
We hated to have to spend more money on a house that we were leaving, but without the document stating that the fireplace was able to be used, it might have become a big deal for the prospective owners, and could break the deal. I tried to see if there was a way of repairing the crack without having to replace the entire panel, but the high temperature mortar couldn't be used on our type of fireplace.
We decided not to risk a problem with any prospective home buyers, so we relented and had the work done on Saturday morning.